Many portable electronic devices include displays for displaying various types of images. Examples of such displays include electrowetting displays (EWDs), liquid crystal displays (LCDs), electrophoretic displays (EPDs), light emitting diode displays (LED displays), etc. In EWD applications, an addressing scheme is utilized to drive the pixels of the EWD. Generally, one of the points of emphasis for EWD applications is low power design since in today's applications, EWDs are intended to be used in mobile and portable media devices.
An input video-stream generally represents a sequence of pixels or subpixels, grouped per line; a sequence of lines, grouped per frame; and a sequence of frames defining a moving video stream (movie). When such a video stream is to be reproduced on an active matrix EWD, a timing controller and display drivers are used to transfer the video data towards the actual pixels of the EWD. A specific addressing scheme is used by the timing controller to timely control row and column drivers of the EWD. The purpose of an addressing scheme is to set (or maintain) the state of a pixel or subpixel in an EWD. The addressing scheme drives an active matrix array or TFT array and provides analog voltages to individual pixels or subpixels of the EWD. These voltages modulate the luminance transmission and/or reflectivity of the pixels or subpixels of the EWD. The pixels or subpixels may be grouped per row and when a row is addressed, voltages of a complete row are stored as charge on corresponding pixel or subpixel capacitors. As the video-data is repeatedly updated, still and moving images can be reproduced by the EWD.
Each address cycle consumes an amount of energy. Furthermore, leakage of the pixel or subpixel capacitors (e.g. current through active matrix switches and dielectric materials) causes a reduction in transmission/reflectivity. Additionally, backflow of electrowetting fluids of the EWD is another cause of reducing transmission/reflectivity. Reset pulses used in EWDs also cause a temporary reduction of transmission/reflectivity. The temporary reduction of transmission/reflectivity is observed as a reduction in luminance.